This invention relates generally to electronic oven control circuits and, more particularly, to an electronic oven control circuit for a gas oven having a hot surface igniter.
Gas oven control systems which utilize hot surface igniters, resistive elements which are heated by the application of electrical current, are widely used because of their durability and reliability. The hot surface igniter is generally positioned in the path of flow of a fuel gas or gas/air mixture, this flow being controlled with an electrically actuable valve. An electronic controller applies current to the igniter until it reaches a temperature high enough to cause ignition of the gas and then provides a signal which causes the valve to open. As the gas passes the hot surface igniter, the gas is ignited and heat is produced.
While such systems are typically very effective, there is always a need for improved systems which provide enhanced functionality at a lower cost. In this regard, the electronic control circuit of the present invention provides a simple and inexpensive hot surface igniter control circuit which has constant current control capability. The hot surface igniter is connected in series between a power supply and a bi-metal operated gas valve. A triac operated under the control of a micro-controller controls the density of pulses applied to the triac and valve. The electrically operated valve is energized to a level which causes it to open only when current passed through the hot surface igniter has heated it to a sufficient gas ignition temperature. A regulating loop is used to monitor the current level in the circuit and to feed this information back to the micro-controller in order to maintain a desired constant current level.
This configuration produces a gas oven control system which is simple and economical as well as which provides improved reliability. These and other features and advantages of the present invention will become apparent upon review of the following description taken in conjunction with the accompanying drawings.